It's a pivotal moment for both parties as the trial preparations unfold in The Staircase episode 3. The quest for evidence and securing witnesses for the jury's deliberation begins. The police initiate a search for the elusive blow poke, missing from the Peterson household. Meanwhile, Martha's homosexuality is revealed, though she's not yet ready to embrace it openly.
Caitlin engages in discussions with Fred and their legal counsel, focusing on reclaiming Kathleen's backpay from Nortel, funds currently being utilized for Peterson's bail and legal expenses. A flashback takes us to Kathleen's encounter with a bat trapped in the attic, the same one that startled her and caused her fall from the ladder in the previous episode.
The prosecution struggles to establish Peterson's infidelity as a motive for Kathleen's murder. A breakthrough occurs when Dennis Rowe, a character from the previous episode's fundraiser, emerges as a potential lead. Rowe claims to have had multiple sexual encounters with Michael, causing a rift between the brothers, Michael and Bill. Bill reveals he's taking a two-week break to visit his family.
At SBI, the team relentlessly pursues evidence to prove Kathleen's death was a result of a blunt force trauma. We witness multiple molds of her head being utilized to validate their theory. Rowe lists his sexual partners, shocking DA Hardin with the revelation that many of them are donors to his political campaign. This leaves Hardin hesitant to call Rowe to the stand and expose his acquaintances.
Flashbacks expose Peterson's unfaithfulness, revealing his oral encounter with Tyrone in an adult entertainment shop. In the present, Tyrone warns Dennis against associating him with the trial. The documentary continues, offering an off-camera glimpse of the documentarians arguing over Michael's innocence, their views diametrically opposed. Martha and Margaret agree to an interview, aiming to portray Mike in a favorable light. Caitlin and Fred successfully redirect the Nortel payments to themselves as next of kin, leaving the Peterson team anxious about funding the ongoing trial.
The interview hits the airwaves, and Margaret Blair, the woman on the phone during Christmas in episode 2, is revealed to be Liz's sister—Liz, the biological mother of Martha and Margaret. Unlike the original sensational documentary, this revelation is more subdued, yet it still shocks. Liz was discovered dead, under mysterious circumstances, just like Kathleen, at the bottom of a staircase. With the trial now only four weeks away, Rudolf and his team are on edge.
The District Attorney now has this crucial information, and the sisters are pondering the bizarre coincidence. Duane, from the State Bureau of Investigation—the same man encountered in the grocery store in the previous episode—contacts DA Hardin, informing him that he is prepared to testify against Mime in court. He has finally pieced together how Mike murdered Kathleen. The Prosecution, with the sisters' consent, decides to exhume Liz's body. The highly anticipated trial commences on July 1st, 2003.
